James r



J. R. ORAVATH.

(No Model.)

- EXGESSIVE CURRENT RECORDER.

Patented July 20, 1897.

Fig-3. P1 9511 5- B E (cu .6 C4 i ge? d WlTNESSES: INVENTOR %.6C W M 72f.

nn Stratus ACTURING OF CHICAGO, ILLINOIS, ASSIGNOR TO run CRAVATHCOMPANY, OF SAME PLACE.

EXCESSlVEMfJURRENT REGORDER.

SPEQILTIUATION forming part of Letters Patent No. 586, 723, dated July20, 1897.

Application filed February 5,1897. Serlalllo. 622,105. (No model.)

To .2.25 whom may concern: I do it known that 1, JAMES R. CRAVATH, a '1on of the United States, residing at Chii ill be county of ook and Stateof lllic in vented a certain new and useful mcnt in Excessive-CurrentRecorders, of which the following is a full, clear, concise, and exactdescription, reference be ing; had to the accompanying drawings, forminga part of this SPGClfiCEtlJlOH.

lily invention relates toan excessive-current recorder for affording acomparative record of the excessive currents employed in the operationof several electrical devices, and is mrticularly applicable toelectric-railway systems, where it is desirable to obtain a comparativerecord of the excessive currents used by the several motormen in therunning of their cars or trains, whereby a comparison of the efficiencyof the motormen may be ob tained.

it is well known among those having the management of electric-railwaysystems in charge that some motormen are very wasteful 5 and careless inthe use of electric current in running their cars, thereby causing unduestrain on the power plant and car equipments and waste of power It istherefore desirable-to have some recording device to enable a manager todetermine which of the motormen have been careless in usin excessivecurrent.

itis the object of the present invention to provide a recording devicewhich may be used for this purpose and which, while effective inoperation, maybe constructed and operated at small cost and with littleliability for error incommon daily use.

i in the preferred form of m y invention I provide in connection witheach of the motors or other devices the excessive currents through whichare to be compared a conduc tor or wire connected in series with theelec trical device and adapted to be heated by the s ge of the currenttherethrough. Rest- 1 the heating-conductor and extend- ,uistc sclythereto is a thin strip or t of alloy or other fusible metal adaptedmelt at a comparatively low temperature.

" passage of a currentin excess of cterinined maximum the fusible ismelted by contact with the heatingconductor and descends, preferably, bythe assistance of a weight depending from the lower end thereof, theheatingconductor thus meltingits way through the sheet of metal in alongitudinal direction. I The distance through which theheating-conductor has melted away the metal affords a comparativemeasure of the excessive currents which have traversed the circuit whencompared with the extent of melting of fusible strips employed uponother similar circuits having heating-conductors of the same dimensionsand a fusible metal of the same meltingpoint and thickness.

The fusible strip,-being made of metal which is a conductor ofelectricity, must be made thin, so that it will not afford a bypath toshunt any considerable portion of the current past the heating-conductorwhen the current to be recorded is passed directly therethroug'h. As themetal is also a condoctor of heat, the making of the strip of fusiblemetal thin is further necessitated in order that the metallic strip maynot conduct away any considerable portion of the heat of theheating-conductor. In the employment of the fusible metal I have for theabove reasons found itessential to make the metal of small thicknesswhere it rests in contact with the heating-conductor.

It is further essential to make the thickness of the metal uniformthroughout its entire length and to use metal strips of the samethickness and melting temperature upon circuits which are to becompared, and to subject them to the action of heating-conductors ofexactly the same dimensions.

In practice I have thus formed the metal into a thin flat sheet or stripadapted to rest 0 by the end upon the heating-conductor. It 1s apparent,however, that the thin sheet, instead of being made fiat, may assumeother forms, provided it has a thin-edge or edges resting transverselyin heatconductive con tact with the heatingconductor.

The electric current maybe passed directly through the heating-conductoror the heat generated by the electrical conductor may be indirectlyconveyed to the heating-conductor. 100 The term heating-conductor asemployed herein refers to the conductor against which the sheet offusible metal rests and which conveys the heat to the fusible metal tomelt the same, whether it be a part of the electrical circuit or not.Throughout this specification I have employed the termffusible metalascomprehending alloysthat is,mix-

In all 'casesthe fusing temperature of the heating-conductor should bemuch above that of the fusible sheet, in order that there may I be nodanger of melting the heating-conductor by the heat developed.

The fusing 'te m-perat-u-re of the fusible metal is so adjusted that thefusible metal does not melt to any appreciable extent until theheating-conductor has been subjected to a current above thepredetermined value.

As a practical illustration of .the application of my invention toelectric-railway motors it may be supposed that sixty amperes is themaximum current a motorman should ordinarily use in the operation of acertain type ure proportional to the excessive currents which havepassed through the several electricalfi'vices. I amaware that thedescent of the fusible metal willnot afford an accurate record of theampere hours of current passing through any circuit over and abovefusible metal will be'theoretically propor tional to the square of theexcessive current flowing. This fact, however, is of practical value intheu'se of the recorders, since it is desirable that the record of thegreatly excessive currents should be magnified and accentuated, becauseit is these greatly excess 'ive currents that wreck the car equipmentand make necessary' the running of machinery of greater capacity at thepower-station and a correspondingly greater investment in power plantand feeders.

The recorders of the present invention are' valuable as affording acomparative measure of the efliclency of the various motormen and not asan absolute record in electrical units.

The distance through which the heating-0on of fusible metal, the coverof the box being open. Fig. 2 is a view of the metallic casing for therecorder-box. Fig. 3 is a view of the recorder-box closed. Fig. 4; is asectional view of line 4 4, Fig. 1. Figs. 5 and 6 are troller-box.

face and edge views of the strip of fusible metal and weight. thecontacts on the recorder-box and on the bottom board of the casing.gramillustrating the use of the recorders with the motors'of anelectric-railway system.

Like letters'refer to like parts in the several figures. Therecorder-box com prises a base-board a, to which is hinged a door a,which may be secured in a closed position by a look a? of, controlled bya key. A longit dinal slot a is provided in the upper end of the base,in which; rests edgewise the strip or sheet I; of

fusible metal, which rests at the lower end in contact with theheating-conductor 0, held at the ends in binding-posts c c, secured tothe base a and provided with binding-screws The binding-posts arearranged so that the heating-conductor may be removed by lifting thesame laterally out of the channels provided in the binding-posts. Belowthe heating-conductor a channel a is provided in the base-board a, inwhich moves the weight 01, which is adapted to be attached to the lowerend of the strip of fusible metal. Upon Fig. 7 is a detail view of Fig.8 is a dia-- the upper end of the weight are provided hooks d d, whichfit in holes b b, provided in the lower end of the strip of fusiblemetal. In order that the weight may be rocked slightly laterally topermit the passage of the ends of the hooks dd. through the holes b b,the sides of the weight are-maderoundedr Upon the face of the doororcovers are, BZoVided hahdles or straps e e'to facilitate the. ndlingof the recorder-box. sixty amperes, because the movement of the When inposition, the recorder-box rests within the metallic casing f, which isseemed in position at some convenient location on the car, preferably atthe side of the com A hinged door f is provided for. the casing, whichmay be secured in enclosed position by the nuts f' f, screwi'ng the lugsf f In the bottom of the-casing is provided a baseboard g, of wood orother insulating material, upon which are mounted contact-posts g g, towhich the circuit'wiresare connected, the circuit-wirespassing downwardin the grooves or channels 9 g and to r the exterior of the casingthrough holes g g;

The conprovided in the lower end thereof.- tact-posts g g are providedwith blades g 9 between which passthe blades 0 0, provided upon the rearof the binding-posts c e,-the blades 0 a being extended through openingsprovided in the base-board a of the recorder box. When the recorder-boxis placed in the casing, the blades 0 c of the binding-posts on therecorder-box engage, respectively, the

blades of the contact posts g g, carried in the casing, thus closing thecircuit through the heating-conductor, and by the removal of therecorder-box from the casing the circuit is opened.

The recorder-boxes may be under the control ofgan employee whose duty itis to prepare the boxes by properly placing the strips of fusible metaltherein, and these boxes already locked may be handed each day to theseveral motormen, who place them in the easin'gs on their respectivecars.

As the motorcircuit is open until'the recorder-box is placed in positionthe motorman must place his recorder-box in position before he can starthis car. Any attempt to operate the car in the absence of therecorder-box by short-circuiting the contact-posts would be readilydetected by the inspector. The casings and recorder-boxes are all madealike, so that the recorder-boxes are-interchangeable and can be placedin any of the casings. At the end of the day the recorder-boxes may bereturned by the motormen. In this manner the motormen have no controlover the recorders for the purpose of tampering with the operationthereof or the records made thereby, while the labor of keeping therecords is reduced to a minimum.

The recorder-box is constructed to snugly fit the casing, and the doorof the casing cannot be closed until the recorder-box is thrustcompletely into position. The bottom of the recorder-box fits tightlyagainst the base board in the back of the casing, so that when therecorder-box is in position and the easing-door closed there is not roomfor the plac ing of any body, as a wire or conductor, be-

tween the back of the recorder-box and the back of the casing, and ifsuch a conductor be placed in position for the purpose ofshortcircuiting the contact-posts on the casing the recorder-boxcannot-be placed in position and the door of the casing closed, and suchattempt to short-circuit the recorder-box would be frustrated.

In Fig. 8 I have illustrated in diagram the application of theexcessive-current record'- ers to the several cars of anelectric-railway system. The generator 7L supplies current to thetrolley-wire h, with which the trolley-' arms 7t 7t make contact andconvey current through the motors ,Z Z, mounted on the cars in m; Inseries with each of the motors is included the heatin g-conductor 0,upon Whiclr The eX-, tent of melting of the several strips of fusiblemetal divided by the number of miles the rests the strip 7) of fusiblemetal.

respective cars have run affords a comparatlve indication of therelative efficiency with which the several cars have been operated.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is

1. The combination with a thin sheet of fusible metal, of aheating-conductor extending transversely thereto and heated by anelectric current'to cause said conductor to melt its way through saidsheet of fusible metal, substantially as described.

2. The combination with a recorder-box, of a heating-conductor and abody of fusible material contained therein, a casing for the receptionof said recorderbox, contacts provided upon said casing and connectedwith the working circuit, contacts upon said.1'ecorder-box connectedwith the heating-conductor and arranged to engage the contacts in thecasin g when the recorder-box is placed therein to complete the circuitthrough the heating-conductor and to break contact therei with upon theremoval of the recorder-box to open the working circuit, substantiallyas described.

3. The combination with a casing provided with a cover or door andcarrying contacts connected with the working circuit, of a recorder-boxcarrying the heating-conductor and the fusible material, and providedwith contacts for engaging the contacts of said casing, said recorderbox being constructed to snugly fit said casing and to rest against thebottom thereof and preventing the closing of the door of the casinguntil the recorder-box is placed completely in position, substantiallyas described.

at. The combination with the recordenbox provided with a pair ofcontact-terminals, of go a transverse electrical conductor Within saidbox connected in circuit between said terminals, a narrow slot abovesaid conductor and a thin sheet of fusible metal therein and restingupon said conductor, the plane of said slot being perpendicular to saidconductor, a channel beneath said conductor and a weight moving therein,substantially as described.

, In witness whereof I have hereunto subscribed my name in the presenceof two witroo nesses.

JAMES R. ORAVATII.

Witnesses W. CLYDE Jones, M. R. Roonronn.

